[Acoustic reflection technique].

Acoustic reflection technique has been employed to assess the pharyngeal cross-sectional area in sleep apnea patients. It has the advantage of being noninvasive and quick, and it also allows for continuous evaluation of the patency of these regions. The technique, however, has never been used during sleep because of its restrictions. This issue overlook the recent progress of the technique, i.e., the newly developed nasal acoustic reflection technique which enabled us to assess the pharyngeal cross-sectional area during sleep. Application of this technique includes a method of determining the site of pharyngeal occlusion, a method of evaluating the efficiency of various therapeutic methods of sleep apnea, and a method of measuring the upper airway collapsibility during sleep.